Core release spray application method and apparatus

ABSTRACT

A method for forming a core includes the step of providing a corebox defining in a closed configuration thereof a closed internal core-forming cavity and providing at least one external opening through the corebox into said cavity in the closed configuration ( 902 ). A core release substance is applied through the opening directly onto at least one surface of the closed core-forming cavity with the corebox in the closed configuration ( 904 ). A forming material is added to the cavity ( 906 ) followed by an addition of a core bonding agent ( 908 ). A core that has formed in said closed core-forming cavity is allowed to dry and removed from the cavity ( 910 ).

FIELD OF THE INVENTION

This invention relates to casting methods, including but not limitedmethods used to form cores for use in casting molds.

BACKGROUND OF THE INVENTION

A typical sand casting operation includes a series of steps or processesfor forming and preparing a mold for casting. A model or pattern for acomponent to be cast is created and used to form a mold and variousinternal cores, as is known in the art. The same model is typically usedto create a large number of molds. The molds and cores created aretypically made by compaction of a granular material such as sand thathas a high resistance to heat. The sand used to form cores is furtherbonded to retain its shape by an appropriate material, for example, anepoxy or phenolic material.

Tooling for forming cores, or coreboxes, are typically assembled from atleast two, typically three or four, separate pieces to facilitatehandling and forming of the cores. In a previous process, a formingoperation for internal cores begins with at least two exterior pieces oftooling dies that form a cavity between them when assembled. The toolingdies are laid open and sprayed with a core release spray. Non coreforming surfaces of the tooling dies are washed or blown clean to removecore release overspray, and the tooling is closed. Subsequent to closingthe tooling, sand and a bonding agent are added in the cavity to formthe core, and the tooling is opened to eject the completed core. Thetooling is cleaned once more using compressed air or an appropriatewashing agent, and the process is repeated.

A major disadvantage of the traditional spraying application for thecore release substance is that much of the core releases substance iswasted. Spraying onto the tooling uses more of the substance than isnecessary for the core contact areas of the tooling, due to overspray,and yet is not effective in ensuring that the core release substancewill adequately cover the intricate core forming surfaces of the toolingdies. Moreover, open spraying of the core release substance onto thetooling dies releases particles of the substance to the atmosphere.

Accordingly, there is a need for a more effective and economical methodof applying a core release substance onto core forming tooling dies in acorebox.

SUMMARY OF THE INVENTION

A core-forming apparatus includes a multipiece corebox defining in aclosed configuration thereof an internal cavity with at least oneopening into the internal cavity in the closed configuration and anexternally-supplied spray head for dispensing a core release substance.The spray head is disposed inside the corebox through the opening tospray the core release substance directly onto a surface of the internalcavity while the corebox is closed, thereby avoiding overspray ontonon-core-forming surfaces of the corebox.

A method for forming a core includes the steps of providing amulti-piece corebox defining in a closed configuration thereof a closedinternal core-forming cavity and providing an external opening throughthe corebox into said cavity in the closed configuration. With thecorebox in the closed configuration, a core release substance is appliedthrough the opening directly onto at least one surface of the closedcore-forming cavity. A core forming material is then added into thecavity and a core bonding agent in injected into the cavity. Finally, acore that has formed in the cavity is allowed to dry and is subsequentlyremoved.

Another method for forming a core for use in a casting operationincludes the step of connecting a tooling mold having a closedconfiguration defining a closed internal cavity and an opening from theclosed internal cavity through the tooling mold to a first shuttle. Theinternal cavity is filled with sand through the opening and the openingthrough the tooling mold is then connected to a second shuttle. The sandthat has filled the cavity is injected with a bonding agent and allowedto cure and form a casting core. The tooling mold is opened, and theformed casting core is ejected and removed from the tooling mold. Thetooling mold is closed and then the opening through the tooling isconnected to a third shuttle. With the tooling mold closed, the cavityis sprayed with a core release substance through a spray head extendingthrough the opening that is connected on the third shuttle, and the corerelease substance is allowed to dry and be ready for the next coreforming operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of prior art tooling dies used for formingcores used in casting operations.

FIG. 2 is an illustration of the tooling dies of FIG. 1 placed on aconveyor system and undergoing a core release substance coating process.

FIGS. 3A-3D are illustrations of successive steps employed in the priorart process to assemble a corebox, fill a cavity with sand, add abonding agent to the cavity, and open the corebox to eject and remove anewly formed core.

FIG. 4 is an illustration of spraying a closed corebox with a corerelease substance in accordance with the invention.

FIGS. 5A-5C are illustrations of successive steps employed to fill acavity of the previously-coated corebox cavity of FIG. 4 with sand, adda bonding agent, and open the corebox to eject and remove a newly formedcore, in accordance with the invention.

FIG. 6 is an illustration of an alternate embodiment of a coreboxundergoing a deposition process of a core release substance having aspray head inserted into a mold cavity through more than one opening inaccordance with the invention.

FIG. 7 is an illustration of a closed corebox undergoing an automateddeposition process of a core release substance having a spray headinserted into a mold cavity in accordance with the invention.

FIG. 8 is an illustration of a closed corebox undergoing a manualdeposition process of a core release substance having a spray headinserted into a mold cavity in accordance with the invention.

FIG. 9 is a flowchart for a method of forming a core in accordance withthe invention.

FIG. 10 is a flowchart for a method of forming a core for use in acasting operation in accordance with the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

The following describes an apparatus for and method of creating a sandcore for use in casting a component. In prior processes, a core releasesubstance, used to facilitate removal of a core from the tooling used toform it, is sprayed into a tooling cavity while the tooling is in anopen position. A typical process for creating a core 100 is illustratedin FIG. 1. A first tooling die 102 may have a core forming surface 104,a die contact surface 106, and an exterior surface 108. A passage 110connects the core-forming surface 104 with the exterior surface 108. Asecond tooling die 112 is constructed to mate with the first tooling die102, and has a core-forming surface 114, a die contact surface 116, andan exterior surface 118.

In a typical prior core-forming operation, a process begins withspraying a core release substance onto the dies 102 and 112, as shown inFIG. 2. A conveyor system 200 may be used to carry the dies 102 and 112to a spray station 201. When in the spray station 201, a spray head 202that is either manually or electronically controlled sprays a layer 204of a core release substance 206 onto the internal surfaces 104 and 114,as well as on the contact surfaces 106 and 116, and even on some of theexternal surfaces 108 and 118 due to overspray. The core releasesubstance or material 206 is intended to prevent bonding of the corematerial to the internal surfaces 104 and 114 of the dies 102 and 112.

Although some quantity of the substance 206 is deposited onto thesurfaces 104 and 114 that lie between the mold pieces 103 and 120 whenassembled, the layer 204 that has been deposited onto surfaces 106 and116 is removed, typically by scraping or blowing the excess materialoff, to ensure that the dies 102 and 112 fit together well for thesubsequent core forming operation. This additional scraping or blowingoperation is time consuming and also releases particles into the air.Moreover, the sprayer 202 may not adequately deposit enough of the corerelease substance 206 into deep crevasses and hard-to-reach areas anddepressions of the dies 102 and 112.

The coated dies 102 and 112 are assembled as shown in FIG. 3A to form aninternal cavity 302. At this point in the process, the dies 102 and 112are ready to form the core 100 in the cavity 302. A first shuttle 304connects to the opening 110 and deposits a core forming material 306, asshown in FIG. 3B. A shuttle as used in this process denotes amechanically or manually manipulated machine element that is capable ofoperably connecting to the opening 110. When the material 306 has filledthe cavity 302, a second shuttle 308, which may connect to opening 110or another opening, injects a bonding agent 310 into the cavity 302 asshown in FIG. 3C. The bonding agent 310, advantageously in gaseous form,bonds the material 306 to form the core 100. When the core 100 issufficiently bonded, the shuttle 308 is removed, the dies 102 and 112open, and the core 100 is ejected as shown in FIG. 3D. After completionof a cleaning process of the dies 102 and 112 that removes left overcore material that may have adhered to the surfaces 104 and 114, theprocess is repeated. This typical process has a few disadvantages.First, the process of creation of the layer 204 onto the dies 102 and112 requires an additional cleaning operation to remove the core releasematerial 206 that is deposited due to overspray onto unnecessarysurfaces. Second, the spray station 201 may release particles of the 206material into the air thus increasing an airborne particle content ofair at a facility where it is used. Third, the core release materialthat is not sprayed in the core-forming surfaces 104 and 114 is wastedand accordingly increases the processing costs and processing time.These and other disadvantages may be rectified by use of an improved diepreparation process, as follows.

A first die 402 and a second die 404 may be assembled before applicationof a core release material, as shown in FIG. 4. The assembled dies 402and 404 yield a corebox 406 having a closed configuration which has aclosed internal cavity 408 and at least one opening or port 410 from theinternal cavity 408 to the exterior of the corebox 406. A first shuttle412 connects to the opening 410 and deposits a core release material 406onto at least a portion of an internal surface 414 of the cavity 408.The first shuttle 412 may further include a spray head 405 may extendinto the internal cavity to provide more uniform coating of the cavitysurfaces. Examples of suitable core release materials include asubstance marketed under “Zip slip 121S,” supplied by AshlandCorporation, and “Cobra 15 N,” supplied by the Hill & GriffithCorporation. A layer 416 of core release material 406 is created aroundthe cavity 408. The corebox 406 is now ready to form a core 500.

The process of forming the core 500 following the internal deposition ofthe layer 416 onto the cavity 408 while the dies 402 and 404 areassembled is similar to a typical core forming process. A second shuttle502 connects to the cavity opening 410, or another opening if desired,to deposit a core forming material 506, as shown in FIG. 5A. When thematerial 506 has filled the cavity 408, a second shuttle 508, which mayconnect to opening 410 or another opening, injects a bonding agent 510into the cavity 408 as shown in FIG. 5B. The bonding agent 510,advantageously in gaseous form, bonds the material 506 to form the core500. When the core 500 is sufficiently bonded, the shuttle 508 isremoved, the dies 402 and 404 open, and the core 500 is ejected as shownin FIG. 5C. The process may be repeated to form additional cores.

Application of a core release substance within an internal cavity of acorebox in a closed configuration is also advantageous for coreboxeshaving intricate internal cavities or internal core features, as shownin FIG. 6. In this embodiment, a corebox 600, when assembled out of twoor more individual tooling dies, includes an internal cavity 602, afirst opening 604 and a second opening 606. A first internal feature 608is positioned within the cavity 602 and may be connected to a secondinternal feature 610. Both internal features 608 and 610 may beconnected to each other, and may be connected to an internal wall orsurface 612 of the internal cavity 602. The corebox 600 may be made byassembly of numerous dies similar to the assembly process discussedabove.

In the application of a core release substance 614, a spray head 616,supported by an advantageously flexible arm 618, may be inserted intothe cavity 602 through the opening 604. A layer 620 of a core releasesubstance 614 is advantageously sprayed onto a portion of the surface612 adjacent to the spray head 616. The spray head 616 is subsequentlyremoved to allow the layer 620 to dry. The spray head 616 may then beinserted through the opening 606, shown in the alternative locationdenoted by dashed lines, to continue spraying the layer 620 onto anotherportion of the surface 612. The spray head may continue entering thecavity 602 as many times and through as many openings as is required tocover the surface 612 substantially, or more than 90%, with the layer620.

Each of the openings 604 and/or 606 may be openings formed especially toallow the spray head 616 to enter into the cavity 602, but mayadvantageously be openings formed in the corebox 600 for other reasons,such as to insert a spray nozzle to dispense core forming material, tosupply a bonding agent or resin to cure the core material, to help ejecta formed core from the cavity 602, and so forth. Furthermore, theflexible arm 618 may be configured for manual or mechanical control ofmotion, and may advantageously be agile enough to maneuver the sprayhead 616 thorough intricate passages that lead from the outside of thecorebox 600 into the internal cavity 602. The flexible 618 arm mayadvantageously be capable of axial and rotational motion along threeaxes.

In the embodiment shown in FIG. 7, a corebox 700 having an internalcavity 701 may be carried through a manufacturing facility on a conveyorsystem 702 in an assembled state up to a spray station 704. The station704 may include a base unit 706 connected to an electronic controller708. The electronic controller 708 may also be connected to varioussensors (not shown) or other controllers (not shown) that may relayinformation to the controller 708, such as, a position of the corebox700 and other coreboxes (not shown) on the conveyor system 702, and soforth. The controller 708 may be pre-programmed with a location of anopening 710 on the corebox 700 that provides access to the internalcavity 701. The controller 708 may control and guide a plurality or armsor, in general, a shuttle or control mechanism 712. The controlmechanism 712 may be capable of supplying a substance to a spray head714 located at a distal end of the mechanism 712. The controller 708 mayguide the spray head 714 through the opening 710 and into the cavity701. Alternatively, the spray head 714 may be adapted to attach to theopening 710 and have at least one spray nozzle (not shown) attachedthereon that is aimed toward the cavity 701. The controller 708 may theninitiate spraying a core release substance 716 into the cavity 701. Inthe case where more than one opening are available and/or required forsatisfactory coverage of the cavity 701 with the substance 716, thecontroller 708 may retract the mechanism 712 from the opening 710 andre-insert in into another opening (not shown) as required.

In the embodiment shown in FIG. 8, a corebox 800 having an internalcavity 801 with an opening 810 is carried in an assembled state up to aspray station 804 by a conveyor system 802. The station 804 may includea base unit 806 controlled by an operator 808. The operator 808 may becapable of halting the motion of the corebox 800 within a specifiedlocation along the conveyor system 802, adjacent to the station 804. Theoperator 808 may control and guide a shuttle or manual mechanism 812.The mechanism 812 may be capable of supplying a substance to a sprayhead 814 located at a distal end of the mechanism 812. The operator 808may guide the spray head 814 through the opening 810 and into the cavity801. The operator 808 may then initiate spraying a core releasesubstance 816 into the cavity 801. In the case where more than oneopening is available and/or required for satisfactory coverage of thecavity 801 with the substance 816, the operator 808 may retract themechanism 812 from the opening 810 and re-insert in into another opening(not shown) as required.

A flowchart for a method of forming a core for use in a mold for castinga component is shown in FIG. 9. A multi-piece corebox is provided atstep 902 that defines, in a closed configuration thereof, a closedinternal core-forming cavity and an external opening through thecorebox. A core release substance is applied through the openingdirectly onto at least one surface of the closed core-forming cavity,with the corebox still in the closed configuration, at step 904. A coreforming material, for example sand, is added into the closedcore-forming cavity at step 906. A core bonding agent is added to theclosed core-forming cavity at step 908 to bond core forming materialthat has completely filled the cavity. A core that has formed in theclosed core-forming cavity is allowed to dry and is then removed fromthe corebox at step 910. An optional washing of the corebox when in anopen configuration may be used to clean leftover core forming material.One example of a core wash substance is known as “4783” and is suppliedby the Delta HA Corporation that can be used to advantageously clean themold piece and provide a smoother casting surface.

The core release substance that is applied through the opening directlyonto at least one surface of the closed core-forming cavity, with thecorebox still in the closed configuration, may advantageously be appliedby spraying the core release substance from a spray head that isinserted within the internal core cavity through the opening, and/or aspray head that attaches to the opening and has, for example, a nozzlethat is aimed toward the cavity. The spray head may be carried by ashuttle, or in this case, an automated piece of a machine that isarranged to automatically deploy and attach to the corebox at anappropriate location that aligns the spray head with the opening.

A flowchart for a method of forming cores for use in a casting operationis shown in FIG. 10. A tooling mold having a closed configuration thatdefines a closed internal cavity and an opening from the closed internalcavity through the tooling mold is connected to a first shuttle at step1002. The closed internal cavity is filled with sand through the openingat step 1004. The tooling mold is connected to a second shuttle, and thesand in the closed internal cavity is injected with a bonding agent atstep 1006. The sand in the closed internal cavity is allowed to cure andform a casting core at step 1008. The tooling mold is opened, and theformed core is ejected and removed from the tooling mold at step 1010.The tooling mold is closed at step 1012. The closed tooling mold isconnected to a third shuttle at the opening at step 1014. The closedinternal cavity is sprayed with a core release substance through a sprayhead that is connected on the third shuttle and extends through theopening at step 1016. The core release substance is allowed to dry atstep 1018, and the tooling mold is now ready to be used for forminganother core.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges that come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. An apparatus comprising: a corebox for forming a core for a castcomponent having a closed configuration and defining a closed internalcavity having at least one opening operatively connecting the cavitywith an exterior surface of the corebox; a spray head for dispensing acore release substance disposed in operative engagement with saidopening; wherein the spray head is disposed to spray the core releasesubstance onto at least one internal surface of the internal cavity withthe corebox in the closed configuration.
 2. The apparatus of claim 1,wherein the corebox includes at least two mold pieces, and wherein eachof the at least two mold pieces are connected to each other to form saidclosed configuration.
 3. The apparatus of claim 1, wherein the internalcavity has a second opening, and wherein the spray head enters thesecond opening to spray an additional quantity of the core releasesubstance.
 4. The apparatus of claim 1, wherein the at least one openingis a passage through which a core forming material is added to thecorebox.
 5. The apparatus of claim 1, wherein the spray head has atleast one spray nozzle attached thereon, and wherein the at least onespray nozzle has an orifice through which the core release substance issprayed.
 6. The apparatus of claim 1, wherein the spray head has freedomof axial motion and freedom of rotation along three axes.
 7. Theapparatus of claim 1, further comprising an electronic controller,wherein at least one of a motion and a rotation of the spray head iscontrolled by the electronic controller.
 8. The apparatus of claim 1,wherein the spray head is controlled manually by an operator.
 9. Theapparatus of claim 1, further comprising a shuttle that is connectableto the core box, wherein the spray head is disposed on the shuttle. 10.The apparatus of claim 1 wherein the spray head is disposed duringoperation within the cavity through the opening to spray the corerelease substance therewithin.
 11. A method for forming a core,comprising the steps of: providing a multipiece corebox defining in aclosed configuration thereof a closed internal core-forming cavity andproviding an external opening through the corebox into said cavity;applying a core release substance through the opening directly onto atleast one surface of the closed core-forming cavity with the corebox inthe closed configuration; adding a core forming material into saidclosed core-forming cavity; adding a core bonding agent to said closedcore-forming cavity; and allowing a core that has formed in said closedcore-forming cavity to dry and removing the core from the corebox. 12.The method of claim 11, wherein the application step is accomplished byspraying the core release substance from a spray head that is insertedinto said cavity through the opening.
 13. The method of claim 11,wherein the application step is accomplished by spraying the corerelease substance from a spray head that is connected onto said coreboxat the opening.
 14. The method of claim 12, further comprising the stepof cleaning residual core forming material from the corebox after thepreviously formed core has been removed.
 15. The method of claim 11,wherein the step of application of the core release substance isaccomplished by accelerating the core release substance through at leastone spray nozzle, wherein the at least one spray nozzle is disposed onthe spray head.
 16. The method of claim 11, wherein the core formingmaterial is sand.
 17. A method for forming a core for use in a castingoperation, comprising the steps of: connecting a tooling mold having aclosed configuration defining a closed internal cavity and an openingfrom the closed internal cavity through the tooling mold to a firstshuttle; filling the closed internal cavity with sand through theopening; connecting said tooling mold to a second shuttle and injectingsaid sand in said closed internal cavity with a bonding agent; allowingsaid sand in said closed internal cavity to cure and form a castingcore; opening said tooling mold, ejecting, and removing said castingcore from said tooling mold; closing said tooling mold; connecting saidtooling mold to a third shuttle at said opening; spraying said closedinternal cavity with a core release substance through a spray headextending through the opening that is connected on the third shuttle;and allowing core release substance to dry.
 18. The method of claim 17,further comprising the step of removing loose sand away from saidtooling mold when said tooling mold is open and after said casting corehas been removed.
 19. The method of claim 17, further comprising thestep of disconnecting said third shuttle from said tooling mold andreconnecting said third shuttle to said tooling mold at a secondopening.
 20. The method of claim 17, wherein said tooling mold includesa plurality of cavities, each connected to at least one of a pluralityof corresponding openings.